FISHERY BULLETIN: VOL. 76. NO 2 



30 



20 



r¥m^. 



20 



CD C/1 



FiGL'RE 1. — Values of schooling indices 

 for a school of six Loligo opalescens be- 

 fore and after disturbance (turning on 

 bubbler). Dashed line indicates when 

 air was turned on. Pictures were taken 

 every minute for 64 min. 



30 



--^ 20 



LU •—< 



s:° 10 





for two (Groups 3 and 7) of the experimental runs 

 summarized in Table 1. The parallel orientation is 

 stronger and the variability less in the larger 

 squid (Figure 2C, D). The mean separation dis- 

 tance index is not as clear a function of size (Table 

 1; Figure 2A, B). 



Schools in the Ocean 



Very little is known of the natural behavior of 

 Loligo opalescens when it is not in large mating 

 schools. In many areas, there often is a large con- 

 centration of squid in the vicinity of the deep- 

 scattering layer (C. Recksiek, Moss Landing 

 Marine Laboratories, Moss Landing, CA 95039, 



436 



TIME 



pers. commun., October 1976) and large layered 

 concentrations of L. opalescens have been reported 

 by those involved in submersible exploration (A. 

 Flechsig, Sea Grant Marine Advisory Service, 

 University of California at San Diego, La Jolla, 

 CA 92093, 1973). There is evidence to indicate, 

 however, that L. opalescens is often found in much 

 smaller schools and that these schools contain a 

 narrow size range of individuals. Fields (1965) 

 presents data on the uniformity of size of young 

 squid taken from the same fish catch (presumably 

 the same squid school ) and speculates that the size 

 ranges in the schools he observed represent ap- 

 proximately one-half or less than one-half of a 

 year's growth. 



